Today all artwork becomes digital. The t-shirt art is either created on the computer, scanned into the computer or photographed and loaded into the computer. The image can then be edited in a graphics program such as Illustrator, Corel or Photoshop to prepare it for colour separation. Screen printing involves printing layers of individual colours to create the final composite image. So by using a graphics program the image is separated into its constituent colours. A separate “film positive” or transparency is then output for each colour. The art is now ready for transferring to a screen.
The screens involved in silk screening are just as the name suggests - a fine mesh screen stretched tight on a frame. The screen mesh is completely coated with a thin layer of light sensitive photo-emulsion. The screen is then allowed to dry in a dark cabinet. After it is completely dry, a film positive can be laid over the mesh and it is exposed to light.
The light “fixes” or hardens the emulsion that it strikes. Where the light is blocked by the image area of the film positive the emulsion remains “unfixed”. Subsequently the screen is washed with water. The fixed area of emulsion remain and the unfixed areas of emulsion wash away. This leaves open areas on the screen in the shape of the image. This step is repeated for each colour of ink to be printed.
The screens are then taken to the press - Davies Lakeside Printing has a four and six color manual press - and set up for printing. This involves aligning or “registering” all of the screens so that each colour printed fits together like a puzzle with the other colours and creates the complete image exactly as it was originally created. The screens are clamped into place so that each print will be created exactly the same.